[Beowulf] RHEL7 kernel update for L1TF vulnerability breaks RDMA

Chris Samuel chris at csamuel.org
Mon Sep 10 01:22:13 PDT 2018

On Friday, 17 August 2018 2:47:37 PM AEST Chris Samuel wrote:

> Just a heads up that the 3.10.0-862.11.6.el7.x86_64 kernel from RHEL/CentOS
> that was released to address the most recent Intel CPU problem "L1TF" seems
> to break RDMA (found by a colleague here at Swinburne).

So this CentOS bug has a one line bug fix for this problem!


It's a corker - basically it looks like someone typo'd a ; into an if 
statement, the fix is:

-	if (!rdma_is_port_valid_nospec(device, &ah_attr->port_num));
+	if (!rdma_is_port_valid_nospec(device, &ah_attr->port_num))
 		return -EINVAL;

So it always returns -EINVAL when checking the port as the if becomes a noop.. 

Patch attached...

 Chris Samuel  :  http://www.csamuel.org/  :  Melbourne, VIC
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